1. Field of the Invention
The present invention relates to a rotational laser apparatus capable of forming a measuring reference plane, especially, a horizontal reference plane or any oblique setting plane inclined at a predetermined angle to the horizontal reference plane by means of laser beam.
2. Description of the Prior Art
Conventionally, there is known a rotational laser apparatus for forming a reference line on a laser plane measured with a laser-scanning plane by radiating laser beam from a laser beam source on a wall and so on while rotating the laser beam source. This is referred to as a laser survey machine. The laser plane is horizontally or obliquely formed and then high and low positions of or vertical positions of a point to be measured are determined based on the laser plane as reference.
When hoping to set the laser beam in a predetermined position, for example, an oblique position, data of changing an angler of gradient are input directly from input means into a main body or is set by moving a target which is provided in an radiating position.
Comparing with the direct input by the input means, setting by the target is easy and is relatively mostly used.
FIG. 1 shows a state of changing an angle of gradient at a conventional target 80. Reflecting sections 85a and 85b are composed of mere reflection layers and reflecting sections 84a and 84b are composed of polarized light planes (xcex/4 birefringment members) in addition to the reflection layers. Laser beam is scanned on the reflecting sections to detect a measured position on the reflecting sections and is moved along the reflecting sections by a predetermined distance until the measured position is detected and then is stopped when the measured position is detected.
The laser beam moves to trace a laser plane and changes an angle of gradient thereof when the target is moved.
FIG. 2 shows a signal obtained when the laser beam is scanned on the target.
Basically, the measured point is determined by detection of the reflecting sections 84a and 85b. The reflecting sections 84b and 85a determine clearly rising portions of the signal. The laser beam of circularly polarized light is used to distinguish laser light reflected on a reflected plane. For example, if the target is scanned to obtain time t1 from rise to decay and time t2 from decay to rise and the t1 is not equal to the t2, the laser beam is moved to become t1=t2.
FIG. 3 shows an optical and electrical construction of the rotational laser apparatus. A rotational radiating apparatus 1 comprises a light emitting part 3, a rotated part 2, a reflected-light detecting part 4 and a control part (CPU) 60.
First, the light emitting part 3 will be explained.
A collimator lens 66, a first xcex/4 birefringment member 67 and an holed mirror 68 are arranged in turn from a laser diode 65 side on an optical axis of the laser diode 65 which exits polarized radiating flux of linearly polarized light. The polarized radiating flux of linearly polarized light exited from the laser diode 65 is adapted to parallel by the collimator lens 66 and is changed into circularly polarized light by the first xcex/4 multiple refracting member 67. The polarized radiating flux of circularly polarized light is exited through the holed mirror 68 into the rotated part 2.
The rotated part 2 changes an optical axis of polarized light radiating flux 100 from the light emitting part 3 by 90 degrees and scans the changed flux. A penta-prism 18 of changing the optical axis of the polarized light radiating flux from the light emitting part 3 is provided in a mirror holder 13 to rotate about the optical axis of the polarized light radiating flux. The mirror holder 13 is connected through a scanning gear 17 and a drive gear 16 with a scanning motor 15.
The radiated laser beam from the rotated part 2 is reflected on the target 80 and then polarized light reflected flux from the target 80 is inputted into the rotated part 2. The polarized light reflected flux inputted in the penta-prism 18 is deflected toward the holed mirror 68 which causes the polarized light reflected flux to be incident into the reflected-light detecting part 4.
Next, the reflected-light detecting part 4 will be explained.
A condenser lens 70, a second xcex/4 birefringment member 71, a pinhole 72, a polarized light beam splitter 73 and a first photo-electric transformer 74 are arranged in turn from the holed mirror 68 side on a reflected optical axis of the holed mirror 68. A second photo-electric transformer 75 is disposed on a reflected optical axis of the polarized light beam splitter 73. An output from the first and second photo-electric transformers 74 and 75 is inputted in a reflected-light detecting circuit 76.
The beam splitter 73 divides the polarized light reflected flux inputted in the reflected-light detecting part 4 and causes them to input into the first and second photo-electric transformers 74 and 75. In this case, the second xcex/4 birefringment member 71 and beam splitter 73 are arranged so that the polarized light radiating flux exited from the light emitting part 3 passes through the xcex/4 birefringment member of the reflected plane of the target twice and flux of coinciding with deflected direction of the polarized light reflected flux which has been returned to the main body is inputted into the first photo-electric transformer 74 and the polarized light reflected flux which has been returned to the main body with the same deflected direction as a direction of the polarized light radiating flux exited from the light emitting part 3 is inputted into the second photo-electric transformer 75.
Further, the control part 60 (CPU) will be explained.
A signal from the reflected-light detecting part 4 is inputted into the control part 60. The control part 60 detects as a scanning signal the polarized light radiating flux scans which position of the target 80 from a relationship between the polarized light changing reflected part and a width of a reflected layer in the target 80. A signal from the control part 60 based on the detected position controls an oblique control portion 62 so that the oblique mechanism is driven to oblique the rotated part 2.
However, to detect the position on the target, further an oblique position for getting primarily and to position it, a high detecting ability and a calculating circuit of setting automatically the detection and position are required.
A high accurate light receiving detector and a complex optical system in which resolving ability is high to separate different polarized light fluxes are required for the high detecting ability. A high accurate workability together with a complex structure is, also, required for the complex optical system. The complex and high accurate structure is expensive and easily to damage.
High cost parts must be used to the control part for feeding back immediately detected results to a mechanical part.
Therefore, the rotational laser apparatus capable of performing an oblique setting automatically is expensive necessarily.
The present invention is made in view of the above and an object thereof is to provide a rotational laser apparatus capable of performing an oblique setting without requiring a complex optical system, such as a high accurate light receiver, to separate different polarized fluxes.
The rotational laser apparatus according to the present invention comprises a light emitting part for emitting scanning laser beam toward a target having reflected planes, a rotated part for forming a reference plane with the scanning laser beam from the light emitting part, an oblique mechanism for causing the rotated part to oblique, a light receiving part for receiving light reflected on the target and a control part for controlling the oblique mechanism according to a light receiving signal of the light receiving part.
The target is provided with a plurality of reflected sections transverse to the scanning laser beam.
The reflected sections are disposed in such a manner that a time series arranging state for pulse of the light receiving signal differs between a case that the scanning laser beam intersects the reflected sections from one side to the other side and a case that the laser beam intersects the reflected sections from the other side to the one side, with the same scanning direction of the scanning laser beam.
The control part includes a judging circuit for judging an operated direction of the oblique mechanism based on the time series arranging state for pulse of the light receiving signal.
In one embodiment, the rotational laser apparatus is adapted to form light receiving signal that reflected sections of the target differ in wide along the scanning direction, in the light receiving part.
In the other embodiment, the rotational laser apparatus is adapted to form light receiving signal that reflected sections of the target differ in space along the scanning direction, in the light receiving part.